1. Field of the Invention
The present invention is related to a light guide module, and more particularly, to a light guide module applied in an optical touch module.
2. Description of the Prior Art
The touch screen (touch panel) can be utilized for replacing the mechanical button operation by touch operation through an object or a finger. When a user touches the pattern on the screen, the touch screen can response the touch event by displaying frames or generating sounds according to the operation programs built in the touch screen.
In general, the touch screen can be a resistive touch screen, a capacitive touch screen, an acoustic touch screen, or an optical touch screen. The resistive touch screen uses a spacer to separate two ITO (Indium Tin Oxide) conductive layers; when the user presses the resistive touch screen, the top electrode and the bottom electrode are contacted so that the location of the touch point can be calculated according to the voltage variance on the resistive touch screen. The capacitive touch screen calculates the location of the touch point according to the current induced by the capacitance variance, which is generated by the electrostatic bonding between the arranged transparent electrodes and the human body. In the acoustic touch screen, supersonic waves are transmitted through the surface of the touch panel; when the user touches the surface of the touch panel through a contacting object, the contacting object absorbs supersonic waves so that the touch location can be calculated according to the decay of the supersonic waves.
In the optical touch screen, the light is transmitted through the surface of the touch panel and a sensor generates signal by sensing the light. When the light is blocked by a contacting object at a touch location, the touch location can be obtained by determining where the sensor does not sense the light. The optical touch screen comprises a glass substrate, a lighting component, a sensor, and a lens. The lighting component and the sensor are disposed on the top right corner of the glass substrate. Two reflectors are respectively disposed on the left side and the bottom side of the glass substrate. The lighting component emits the light in various directions to the touch screen and the reflectors reflect the light back to the sensor. When a finger or a contacting object blocks the light, the touch location of the finger (or the contacting object) is obtained according to the signal generated by the sensor sensing the light through the lens.
In the conventional optical touch screen, since the touch location is obtained by the sensor sensing the light reflected by the reflector, the obtained touch location is easily affected by the ambient light. The light reflected by the reflector and the light emitted by the lighting component cause an interaction to the sensor. In addition, since the lighting component disposed on the top right corner of the glass substrate has to illuminate the distant reflectors, the lighting component has to be disposed accurately and the lighting component has to have a higher output brightness and a larger output current.